1. Field of the Invention
The present invention relates to a movable-body apparatus, an exposure apparatus, an exposure method, and a device manufacturing method, more particularly to a movable-body apparatus equipped with a movable body that moves at least in an axis direction within a moving plane, an exposure apparatus is equipped with the movable-body apparatus, an exposure method in which a pattern is formed on an object by exposing it, and a device manufacturing method with the exposure method.
2. Description of the Background Art
Conventionally, in a lithography process, on manufacturing micro devices (electronic devices) such as a semiconductor device, a liquid-crystal display element, etc., a reduction-projection exposure apparatus of a step-and-repeat type (a so-called stepper), a scanning-projection exposure apparatus of a step-and-scan type (a so-called scanning stepper (also called a scanner), etc. is relatively mainly used.
In this type of exposure apparatuses, to transfer a pattern of a reticle (or a mask) onto a plurality of shot areas on a substrate such as a wafer and a glass plate (hereinafter, generally referred to as a “wafer”), a wafer stage that holds the wafer is driven in an XY two-dimensional direction, e.g., by a linear motor etc. Particularly for scanning steppers, not only the wafer stage, but also a reticle stage that holds the reticle is driven by a linear motor etc. in a scan direction within a predetermined stroke. Position measurements of the reticle stage and the wafer stage are generally performed by using a laser interferometer with a good stability of measurements for a long period and a high resolution.
However, due to finer patterns which come from higher integration of semiconductor devices, a positional controllability of stages with a higher precision is required, and now, a short-term fluctuation of measured values caused by a fluctuation of atmospheric temperature on optical paths of beams of laser interferometers has become non-negligible.
On the other hand, recently, an encoder, which is a type of position-measurement devices, with a measurement resolution equivalent to or higher than that of laser interferometers has appeared, and techniques to use the encoder (including a linear scale and a length-measurement device) for position measurement of the wafer stage inside an exposure apparatus have been also proposed (refer, e.g., to Kokai (Japanese Unexamined Patent Application Publication) No. 2004-101362).
However, for encoders described in Kokai (Japanese Unexamined Patent Application Publication) No. 2004-101362, etc., since it was necessary to install a linear scale far from a wafer-mounting position on the wafer stage (a position onto which an exposure light is actually irradiated), there were fears of occurrence of Abbe errors in measurements and upsizing of the external shape of the entire wafer stage.